Retroviral Gag polyproteins are necessary and sufficient for virus budding, but little is known about how thousands of Gag polyproteins are transported to the budding sites. The actin cytoskeleton has long been speculated to take a role in retrovirus assembly and recent studies suggest that HIV-1 assembly is regulated as early as viral RNA nuclear export, however specific mechanisms for these regulations are unknown. In contrast to numerous studies of HIV-1 Gag assembly and budding, relatively little is reported for these fundamental pathways among animal lentiviruses. In this project, we used bimolecular fluorescence complementation (BiFC) (1) to reveal intimate (<15nm) and specific associations between EIAV Gag and actin, but not tubulin; (2) to characterize and compare assembly sites and budding efficiencies of EIAV and HIV-1 Gag in both human and rodent cells when the mRNA nuclear export context is altered to be Rev-dependent or Rev-independent; (3) to reveal co-assembly of Rev-dependent and Rev-independent HIV-1 Gag and rescued assembly of Rev-independent HIV-1 Gag in human cells by in cis provided membrane targeting signals. The results of these studies showed that (1) multimerization of EIAV Gag was required for association with filamentous actin and this association correlated with Gag budding efficiency, suggesting that association of Gag multimers with filamentous actin is important for efficient virion production; (2) HIV-1 and EIAV Gag assembled in different cellular at sites, and HIV-1 but not EIAV Gag assembly was affected by mRNA nuclear export pathways, suggesting that alternative cellular pathways can be adapted for lentiviral Gag assembly and budding; (3) Rev-independent HIV-1 Gag was deficient in lipid raft targeting and its assembly and budding could be restored by membrane targeting signals provided in trans or in cis, suggesting that raft association is critical for HIV-1 assembly and budding and is regulated as early as nuclear export of Gag-encoding mRNA. The findings presented in these studies are significant for public health because a better understanding of the mechanism of retrovirus assembly and budding increase the potential to develop novel antiviral therapies targeting this critical step in the viral life cycle.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-10052007-153423 |
| Date | 30 January 2008 |
| Creators | Jin, Jing |
| Contributors | Linton M. Traub, Simon Barratt Boyes, Ora A. Weisz, Tianyi Wang, Ronald C. Montelaro |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-10052007-153423/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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